This center was originally funded in October 1991 through a NIDA initiative designed to create treatment evaluation centers. Evaluation strategies are based upon the assumption that the patient and treatment characteristics under study can be reliably, validly and sensitively measured. Therefore, the basic measures and instruments that are employed in treatment evaluation studies are the foundation of our knowledge about the effects of treatments. Because of the importance of measurement accuracy and appropriateness in evaluation research we have created a center dedicated to the development, testing and dissemination of evaluation instruments, methods and measures: the Instrument and Methods Development Center (IMDC). The primary, unifying theme of our research in instrument development, and indeed our research in treatment process and outcome is the multi- dimensional measurement of patients and treatments." In our view, the phenomenon of addiction cannot be adequately understood; and addiction treatments cannot be adequately delivered if they focus only on the nature and severity of patients' substance use. A second theme that permeates the work of our Center is "applying these measures and methods to solve real world problems". The large majority of individuals with addiction and substance abuse "problems" are screened, evaluated and referred or treated in: criminal justice settings (prisons, probation, drug courts); welfare settings e.g. "welfare to work" programs); family court and child protective settings (e.g. foster care determinations); unemployment offices and employee assistance programs; and medical settings (e.g. emergency rooms, pre-natal care, infectious disease clinics and/or psychiatric facilities). Because our measurement strategy has recognized the inherent complexity and multi-dimensional nature of the problems presented by addicted individuals; because we have always attempted to use the instruments and methods to solve the day to day questions that faced workers in these settings; and because our instruments have been specifically tested for reliability, validated and utility across many of the settings where addiction is found, these instruments are among the most widely used, across a range of clinical, research and policy settings. We believe that this effort to make measurement instruments and methods clinically and scientifically functional across a range of "real world" environments is a signature quality of our Center separating our work from simply the mechanical assessment of reliability and validity parameters. We plan to continue the general themes of "multi-dimensional measurement" and "application to real world problems" by updating four of our original instruments; by developing a new multi-dimensional measure of the pressures on a patient to enter treatment; and by continuing our "technology transfer' efforts to get the scientific measures and methods developed by research into active and accurate use by treatment providers and policy makers.